352 Transactions. 



Weka Pass. — The exposures of the lower part of tlie Amuri limestone 

 are not very good in the Weka Pass. Morgan, (1915) has noted the following 

 sequence : — 



(1.) Amuri limestone, fairly pure, 40 ft. or less in thickness. This 



is much jointed and even shattered in places. 

 (2.) Amuri limestone, argillaceous, about 40 ft. thick. This rock 

 where exposed to weathering breaks into small cuboidal or 

 irregularly-shaped fragments. 

 (3.) Calcareous light-grey claystone, probably between 40 ft. and 

 50 ft. thick. Exposed surfaces break into very small frag- 

 ments. 

 (4.) Uncemented sand, with lumps of clay. 



Waikare. — An important exposure has recently been made by the excava- 

 tion for soft (surface) limestone in Trounce's pit, a mile west of Waikare. 

 This pit lies on the grassy slopes below the outcrop of the outlier of Amuri 

 limestone, and has passed through the surface deposit of soft limestone into 

 a tough glauconitic mudstone, which exactly resembles those below the 

 Amuri limestone at Weka Creek and the Waipara River. Mr. B. C. Aston 

 has determined the carbonate of lime as 10 per cent. It contains numerous 

 Foramanifera and rare sharks' teeth and brachiopods, including Aetheia 

 sp. cf. gaulteri. 



From borings made in the grassy slopes below the pit, and from the 

 presence of springs farther down, it appears that the above mudstone rests 

 on glauconitic sands, which in turn rest on some impermeable bed, along 

 the top of which a series of springs appears. 



Omihi Creek. — North-north-east of Mount Donald the Amuri limestone 

 and underlying rocks are exposed in a small dry gorge tributary to the 

 main tributary of the Omihi Creek. The lowest beds exposed are about 

 60 ft. of yellow sands, mostly fine-grained but with a fair proportion of 

 large well-rounded quartz grains and much white mica. These become 

 glauconitic and harder 3 ft. from the top, and are succeeded by 15 ft. of 

 glauconitic mudstone, which passes up into 5 ft. of fucoidal argillaceous 

 limestone with a good deal of glauconite. This is succeeded by the con- 

 cretionary band of the Weka Pass stone, here about 6 ft. thick, which in 

 turn is followed by 40 ft. to 50 ft. of typical Weka Pass stone. 



The sands at the base are well exposed farther up the main tributary 

 of the Omihi Creek, and rest upon the Waipara greensands. 



Farther east, although there are no clear exposures, the beds between 

 the Weka Pass stone and the pre-Notocene rocks greatly diminish in thick- 

 ness, and it is probable that no Amuri limestone exists. East of Moore's 

 Hill South the beds below the Weka Pass stone again increase in thickness, 

 and near Davy's farm sands similar to those described above are seen 

 between the Waipara greensands and the Weka -Pass stone. 



# 



Oamaruian. 

 Weka Pass Greensand and Weka Pass Stone. 



The " Weka Pass stone " is an old quarryman's name for the building- 

 stone of the Weka Pass, and was introduced into geological literature by 

 Hutton (1877), who included imder it not only the limestone, formerly 

 used as a building-stone, but also the calcareous greensandstone down into 

 which the limestone passes. McKay referred to the latter rock as the 

 " greensand conglomerate," while Speight and Wild termed it the " nodular 



